title: False multiple exciton recombination and multiple exciton generation signals in semiconductor quantum dots arise from surface charge trapping.
abstract: Multiple exciton recombination (MER) and multiple exciton generation (MEG) are two of the main processes for assessing the usefulness of quantum dots (QDs) in photovoltaic devices. Recent experiments, however, have shown that a firm understanding of both processes is far from well established. By performing surface-dependent measurements on colloidal CdSe QDs, we find that surface-induced charge trapping processes lead to false MER and MEG signals resulting in an inaccurate measurement of these processes. Our results show that surface-induced processes create a significant contribution to the observed discrepancies in both MER and MEG experiments. Spectral signatures in the transient absorption signals reveal the physical origin of these false signals.
authors.affiliation: Department of Chemistry, McGill University, Montreal, Quebec, H3A 2K6, Canada.
authors.forename: Pooja
authors.initials: P
authors.lastname: Tyagi
authors.forename: Patanjali
authors.initials: P
authors.lastname: Kambhampati
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D012666:Semiconductors; D013499:Surface Properties
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide